Thin film solar cell and manufacturing method thereof

ABSTRACT

A thin film solar cell including a substrate, a first conductive layer, a photoelectric conversion layer, a second conductive layer and a passivation layer is provided. The first conductive layer disposed on the substrate has a plurality of first openings, so as to divide the first conductive layer into bottom electrodes of a plurality of photovoltaic elements. The photoelectric conversion layer disposed on the first conductive layer has a plurality of second openings. The second conductive layer is disposed on the photoelectric conversion layer and electrically connected to the first conductive layer through the second openings. The passivation layer is disposed on the sidewall of the photoelectric conversion layer, so that the second conductive layer in the second openings is electrically isolated from the photoelectric conversion layer. A manufacturing method of the thin film solar cell is also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefits of Taiwan patentapplication serial no. 98125100, filed on Jul. 24, 2009, Taiwanapplication serial no. 98139575, filed on Nov. 20, 2009, Taiwanapplication serial no. 98143398, filed on Dec. 17, 2009, Taiwanapplication serial no. 98143392, filed on Dec. 17, 2009 and Taiwanapplication serial no. 98143393, filed on Dec. 17, 2009. The entirety ofeach of the above-mentioned patent applications is hereby incorporatedby reference herein and made a part of specification.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a thin film solar cell and amanufacturing method thereof, and more generally to a thin film solarcell having a passivation layer and a manufacturing method thereof.

2. Description of Related Art

With the raise of the consciousness of environmental protection, theconcept of energy saving and carbon dioxide reduction has graduallydrawn attention, and the development and utilization of renewable energyhave become the focus in the world. A solar cell which converts solarlight into electricity is the most promising in energy industrynowadays, so that manufacturers devote themselves to the manufacturingof the solar cell. Currently, the key issue of the solar cell is theimprovement of the photoelectric conversion efficiency thereof.Therefore, to improve the photoelectric conversion efficiency of thesolar cell means enhancing the product competitiveness.

FIG. 1 schematically illustrates a cross-sectional view of aconventional thin film solar cell. A thin film solar cell 100 includes asubstrate 110, a first conductive layer 120, a photoelectric layer 130and a second conductive layer 140. The thin film solar cell 100 has aplurality of photovoltaic elements 102 connected in series. Thephotoelectric conversion layer 130 is a photoelectric conversionstructure having a PIN junction.

For example, when a light L enters the thin film solar cell 100 fromoutside, electron-hole pairs are generated in the photoelectricconversion layer 130 by the solar energy, and the internal electricfield formed by the PIN junction makes electrons and holes respectivelymove toward the first conductive layer 120 and the second conductivelayer 140, so as to generate a storage state of electricity. Meanwhile,if a load circuit or an electronic device is connected, the electricitycan be provided to drive the circuit or device.

However, in the thin film solar cell 100, the surface recombination ofthe electron-hole pairs easily occurs near the interface S between thesecond conductive layer 140 and the photoelectric conversion layer 130,and thus, the photoelectric conversion efficiency of the thin film solarcell 100 is affected.

SUMMARY OF THE INVENTION

The present invention provides a thin film solar cell, in which therecombination of electron-hole pairs on the surface is reduced, so thata higher photoelectric conversion efficiency is achieved.

The present invention further provides a thin film solar cell, in whichthe short circuit current (Isc) is effectively increased and the leakagecurrent is reduced, so that the photoelectric conversion efficiency andelectric performance are improved.

The present invention also provides a thin film solar cell having abetter photoelectric conversion characteristics.

The present invention provides a manufacturing method to form theabove-mentioned thin film solar cell.

The present invention provides a thin film solar cell including asubstrate, a first conductive layer, a photoelectric conversion layer, asecond conductive layer and a passivation layer. The first conductivelayer disposed on the substrate has a plurality of first openings, so asto divide the first conductive layer into bottom electrodes of aplurality photovoltaic elements. The photoelectric conversion layer isdisposed on the first conductive layer and has a plurality of secondopenings to expose a portion of the first conductive layer. The secondconductive layer is disposed on the photoelectric conversion layer andconnected to the first conductive layer through the second openings,wherein the second conductive layer has a plurality of third openings toexpose a portion of the first conductive layer. The passivation layer isdisposed on a sidewall of each second opening and between thephotoelectric conversion layer and the second conductive layer, so thatthe second conductive layer in the second openings is electricallyisolated from the photoelectric conversion layer.

The present invention provides a manufacturing method of a thin filmsolar cell. A substrate is provided. A first conductive layer is formedon the substrate. A plurality of first openings are formed in the firstconductive layer, so that the first conductive layer is divided tobottom electrodes of a plurality of photovoltaic elements. Aphotoelectric conversion layer is formed on the first conductive layer.A plurality of second openings are formed in the photoelectricconversion layer to expose a portion of the first conductive layer. Apassivation layer is formed on sidewalls of the second openings. Asecond conductive layer is formed on the photoelectric conversion layer,wherein the second conductive layer is connected to the first conductivelayer through the second openings, and the second conductive layer has aplurality of third openings to expose a portion of the first conductivelayer. The passivation layer is disposed between the photoelectricconversion layer and the second conductive layer, so that the secondconductive layer in the second openings is electrically isolated fromthe photoelectric conversion layer.

The present invention further provides a thin film solar cell includinga substrate, a first conductive layer, a photoelectric conversion layer,a second conductive layer and a blocking material. The first conductivelayer disposed on the substrate has a plurality of first openings toexpose a portion of the substrate. The photoelectric conversion layerdisposed on the first conductive layer has a plurality of secondopenings to expose a portion of the first conductive layer, wherein thephotoelectric conversion layer is physically connected to the substratethrough the first openings. The second conductive layer disposed on thephotoelectric conversion layer has a plurality of third openings toexpose a portion of the first conductive layer and a portion of a sidesurface of the photoelectric conversion layer. The third openings and aportion of the second openings are disposed at the same positions, andthe second conductive layer is physically connected to the firstconductive layer through the second openings. The blocking materialfills in the third openings, and at least covers the first conductivelayer and the side surface of the photoelectric conversion layer whichare exposed by the third openings.

The present invention further provides a manufacturing method of a solarcell. A substrate is provided. A first conductive layer is formed on thesubstrate. A plurality of first openings are formed in the firstconductive layer to expose a portion of the substrate. A photoelectricconversion layer is formed on the first conductive layer. A plurality ofsecond openings are formed in the photoelectric conversion layer toexpose a portion of the first conductive layer, wherein thephotoelectric conversion layer is physically connected to the substratethrough the first openings. A second conductive layer is formed on thephotoelectric conversion layer. A plurality of third openings are formedin the second conductive layer to expose a portion of the firstconductive layer and a portion of a side surface of the photoelectricconversion layer, wherein the second conductive layer is physicallyconnected to the first conductive layer through the second openings. Ablocking material fills in the third openings, wherein the blockingmaterial at least covers the first conductive layer and the side surfaceof the photoelectric layer which are exposed by the third openings.

The present invention also provides a thin film solar cell including asubstrate, a first conductive layer, a photovoltaic layer, a secondconductive layer and a passivation layer. The first conductive layerdisposed on the substrate has a plurality of first openings to exposethe substrate. The photovoltaic layer disposed on the first conductivelayer has a plurality of second openings to expose the first conductivelayer. The second conductive layer is disposed on the photovoltaic layerand electrically connected to the first conductive layer through thesecond openings, and has a plurality of third openings to expose thefirst conductive layer and a sidewall of the photovoltaic layer. Thepassivation layer covers the second conductive layer and the sidewall ofthe photoelectric conversion layer in the third openings.

The present invention also provides a manufacturing method of a solarcell. A substrate is provided. A first conductive layer is formed on thesubstrate. The first conductive layer is patterned to form a pluralityof first openings to expose the substrate. A photovoltaic layer isformed on the first conductive layer. The photovoltaic layer ispatterned to form a plurality of second openings to expose the firstconductive layer. A second conductive layer is formed on thephotovoltaic layer, wherein the second conductive layer is electricallyconnected to the first conductive layer through the second openings. Thesecond conductive layer and the photovoltaic layer are patterned to forma plurality of third openings to expose the first conductive layer and asidewall of the photovoltaic layer. A passivation layer is formed tocover the second conductive layer and the sidewall of the photoelectricconversion layer in the third openings.

In view of the above, the thin film solar cell of the present inventionhas the passivation layer disposed between the photoelectric conversionlayer and the second conductive layer, so that the second conductivelayer in the second openings is electrically isolated from thephotoelectric conversion layer. Accordingly, the possibility of thesurface recombination of electron-hole pairs near the interface betweenthe photoelectric conversion layer and the second conductive layer isreduced, and the photoelectric conversion efficiency of the thin filmsolar cell is further improved.

In order to make the aforementioned and other objects, features andadvantages of the present invention comprehensible, a preferredembodiment accompanied with figures is described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 schematically illustrates a cross-sectional view of aconventional thin film solar cell.

FIG. 2 schematically illustrates a local cross-sectional view of a thinfilm solar cell according to an embodiment of the present invention.

FIG. 3A schematically illustrates a local cross-sectional view of aphotoelectric conversion layer of a thin film solar cell according to anembodiment of the present invention.

FIG. 3B schematically illustrates a local cross-sectional view of aphotoelectric conversion layer of a thin film solar cell according toanother embodiment of the present invention.

FIGS. 4A to 4H schematically illustrate a process flow of manufacturinga thin film solar cell according to an embodiment of the presentinvention.

FIG. 5 schematically illustrates a local cross-sectional view of a thinfilm solar cell according to another embodiment of the presentinvention.

FIG. 6 schematically illustrates film layers of a photoelectricconversion layer of a thin film solar cell.

FIGS. 7A to 7H schematically illustrate a process flow of manufacturinga thin film solar cell according to an embodiment of the presentinvention.

FIG. 8 schematically illustrates a local cross-sectional view of a thinfilm solar cell according to yet another embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts.

First Embodiment

FIG. 2 schematically illustrates a local cross-sectional view of a thinfilm solar cell according to an embodiment of the present invention.Referring to FIG. 2, a thin film solar cell 200 includes a substrate210, a first conductive layer 220, a photoelectric conversion layer 230,a second conductive layer 240 and a passivation layer 250. In thisembodiment, the substrate 210 can be a transparent substrate, such as aglass substrate.

The first conductive layer 220 is disposed on the substrate 210 and hasa plurality of first openings T1, and thus, the first conductive layer220 is divided into bottom electrodes of a plurality of photovoltaicelements 202. In this embodiment, the first conductive layer 220 can bea transparent conductive layer, and the material thereof can be at leastone of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zincoxide (ITZO), zinc oxide, aluminium tin oxide (ATO), aluminium zincoxide (AZO), cadmium indium oxide (CIO), cadmium zinc oxide (CZO),gallium zinc oxide (GZO) and fluorine tin oxide (FTO).

In another embodiment (not shown), the first conductive layer 220 can bea stacked layer of a reflective layer (not shown) and theabove-mentioned transparent conductive layer, and the reflective layeris disposed between the transparent conductive layer and the substrate210. The material of the reflective layer can be a metal with higherreflectivity, such as aluminium (Al), silver (Ag), molybdenum (Mo) orcopper (Cu). In addition, the area and number of the photovoltaicelements 202 in the thin film solar cell 200 are not limited by thepresent invention.

The photoelectric conversion layer 230 is disposed on the firstconductive layer 220, and has a plurality of second openings T2 torespectively expose a portion of the first conductive layer 220, asshown in FIG. 2. In this embodiment, the thin film solar cell 200 is athin film solar cell having a single-layer photoelectric conversionlayer. However, the present invention is not limited thereto. In anotherembodiment, the thin film solar cell 200 can be an amorphous siliconthin film solar cell, a microcrystalline silicon thin film solar cell, atandem thin film solar cell or a triple thin film solar cell.

FIG. 3A schematically illustrates a local cross-sectional view of aphotoelectric conversion layer of a thin film solar cell according to anembodiment of the present invention. Referring to FIG. 2 and FIG. 3A, indetails, the above-mentioned photoelectric conversion layer 230 has afirst-type semiconductor layer 232, an intrinsic layer 236 and asecond-type semiconductor layer 234, for example. The first-typesemiconductor layer 232 can be a P-type semiconductor layer, while thesecond-type semiconductor layer 234 can be an N-type semiconductorlayer. In other words, in this embodiment, the photoelectric conversionlayer 230 is a PIN photoelectric structure. In some embodiments, thephotoelectric conversion layer 230 can be a PN photoelectric structurewithout the intrinsic layer 236. In another embodiment, the first-typesemiconductor layer 232 can be an N-type semiconductor layer, while thesecond-type semiconductor layer 234 can be a P-type semiconductor layer.

FIG. 3B schematically illustrates a local cross-sectional view of aphotoelectric conversion layer of a thin film solar cell according to anembodiment of the present invention. Referring to FIG. 2 and FIG. 3B,the above-mentioned photoelectric conversion layer 230 can be adouble-layer photoelectric conversion layer as shown in FIG. 3B, whereinthe photoelectric conversion layer 230 includes a first photoelectricconversion layer 230 a and a second photoelectric conversion layer 230b. In the embodiment as shown in FIG. 3B, the first photoelectricconversion layer 230 a has a first-type semiconductor layer 232 a, afirst intrinsic layer 236 a and a second-type semiconductor layer 234 a,for example. The first-type semiconductor layer 232 a is a P-typesemiconductor layer, while the second-type semiconductor layer 234 a isan N-type semiconductor layer. In another embodiment, the firstphotoelectric layer 230 a can be a PN semiconductor stacked structurewithout the first intrinsic layer 236 a.

Similarly, the second photoelectric conversion layer 230 b has afirst-type semiconductor layer 232 b, a second intrinsic layer 236 b anda second-type semiconductor layer 234 b, for example. The first-typesemiconductor layer 232 a is a P-type semiconductor layer, while thesecond-type semiconductor layer 234 a is an N-type semiconductor layer.Similarly, the second photoelectric conversion layer 230 b is also a PINsemiconductor stacked structure. However, in another embodiment, thesecond photoelectric conversion layer 230 b can also be a PNsemiconductor stacked structure without the second intrinsic layer 236a.

In another embodiment, the first-type semiconductor layer 232 a of thefirst photoelectric conversion layer 230 a and the first-typesemiconductor layer 232 b of the second photoelectric conversion layer230 b can be N-type semiconductor layers, while the second-typesemiconductor layer 234 a of the first photoelectric conversion layer230 a and the second-type semiconductor layer 234 b of the secondphotoelectric conversion layer 230 b can be P-type semiconductor layers.

The photoelectric conversion layer 230 of the above-mentioned embodimentis provided only for illustration purposes, and is not construed aslimiting the stacked number or structure of the photoelectric conversionlayer 230. Persons skilled in the art can adjust the stacked number orstructure of the photoelectric conversion layer 230 upon therequirements.

In the above-mentioned embodiment, the photoelectric conversion layer230 can be a semiconductor thin film including carbon, silicon orgermanium in Group VI of the Periodic Table. For example, thephotoelectric conversion layer 230 includes at least one of a siliconthin film, a carbon thin film, a germanium thin film, a silicon carbidethin film and a silicon germanium thin film, each of which may be inmonocrystalline form, polycrystalline form, amorphous form ormicrocrystalline form, or a combination thereof. Further, in addition tothe silicon thin film, examples of the material of the photoelectricconversion layer 230 can be copper indium gallium diselenide (CIGS),cadmium telluride (CdTe) or a combination thereof. Accordingly, the thinfilm solar cell 200 of this embodiment can be a CIGS solar cell or aCdTe solar cell.

Besides, in some embodiments, the material of the photoelectricconversion layer 230 can be a III-V compound semiconductor thin film, aII-VI compound semiconductor thin film, an organic compoundsemiconductor thin film or a combination thereof. For example, the III-Vcompound semiconductor thin film includes at least one of a galliumarsenide (GaAs) thin film and an indium gallium phosphide (InGaP) thinfilm, or a combination thereof. The II-VI compound semiconductor thinfilm includes at least one of a copper indium diselenide (CIS) thinfilm, a copper indium gallium diselenide (CIGS) thin film and a cadmiumtelluride (CdTe) thin film, or a combination thereof. The organiccompound semiconductor thin film includes a mixture of a conjugatedpolymer donor and PCBM.

Referring to FIG. 2, the second conductive layer 240 is disposed on thephotoelectric conversion layer 230 and electrically connected to thefirst conductive layer 220 through the second openings T2. The secondconductive layer 240 has a plurality of third openings T3 to expose aportion of the first conductive layer 220.

In this embodiment, the second conductive layer 240 can include thematerial of the above-mentioned transparent conductive layer, and thedetails are not iterated herein. In this embodiment, the secondconductive layer 240 can further include a reflective layer disposed onthe transparent conductive layer. It is noted that when the secondconductive layer 240 includes a reflective layer, the first conductivelayer 220 can only be a transparent conductive layer. On the contrary,when the first conductive layer 220 includes a reflective layer, thesecond conductive layer 240 can only be a transparent conductive layerwithout a reflective layer thereon. In an embodiment, each of the firstconductive layer 220 and the second conductive layer 250 can be a singletransparent conductive layer without a reflective layer thereon. Inother words, the design of the first conductive layer 220 and the secondconductive layer 240 can be adjusted according to the users'requirements (e.g. for manufacturing a thin film solar cell withdouble-sided illumination or a thin film solar cell with one-sidedillumination). The design of the first conductive layer 220 and thesecond conductive layer 240 described above is provided only forillustration purposes, and is not construed as limiting the presentinvention.

Particularly, the thin film solar cell 200 has the passivation layer250. The passivation layer 250 is disposed on the sidewall SW of eachsecond opening T2 and between the photoelectric conversion layer 230 andthe second conductive layer 240, so that the second conductive layer 240in the second openings T2 is electrically isolated from thephotoelectric conversion layer 230. In this embodiment, the thickness ofthe passivation layer 250 is substantially between 0.1 nm and 10 nm. Insome embodiments, the thickness of the passivation layer 250 issubstantially between 1 nm and 5 nm. The material of the passivationlayer 250 can be a dielectric material, an insulating material or aoxygen-containing compound. Specifically, the material of thepassivation layer 250 can be an insulating material such as siliconoxide, silicon nitride, silicon oxynitirde or the like.

The thin film solar cell 200 is irradiated by a light (not shown) togenerate electron-hole pairs. The thin film solar cell 200 has thepassivation layer 250 in the second openings T2 between thephotoelectric conversion layer 230 and the second conductive layer 240,so that the second conductive layer 240 in the second openings T2 iselectrically isolated from the photoelectric conversion layer 230, andthe recombination of the electron-hole pairs near the sidewall SW ofeach second opening T2 is further reduced. In other words, as comparedwith the thin film solar cell 100 without the passivation layer 250, thethin film solar cell 200 can exhibit a higher photoelectric conversionefficiency.

A manufacturing method of the above-mentioned thin film solar cell 200is described in the following.

FIGS. 4A to 4H schematically illustrate a process flow of manufacturinga thin film solar cell according to an embodiment of the presentinvention. Referring to FIG. 4A, the above-mentioned substrate 210 isprovided. The substrate 210 can be a glass substrate.

Referring to FIG. 4B, a first conductive layer 220 is formed on thesubstrate 210. In this embodiment, the first conductive layer 220includes the material of the above-mentioned transparent conductivelayer, and the forming method thereof is by performing a sputteringprocess, a metal organic chemical vapour deposition (MOCVD) process oran evaporation process, for example.

Referring to FIG. 4C, a plurality of first openings T1 are foamed in thefirst conductive layer 220, so that the first conductive layer 220 isdivided into bottom electrodes of a plurality of photovoltaic elements.In this embodiment, the method of forming the first openings T1 is byperforming a laser process, an etching process or a removing processusing mechanical force, for example.

Referring to FIG. 4D, the above-mentioned photoelectric conversion layer230 is formed on first conductive layer 220. In this embodiment, themethod of foaming the photoelectric conversion layer 230 is byperforming a radio frequency plasma enhanced chemical vapour deposition(RF PECVD) process, a vary high frequency plasma enhanced chemicalvapour deposition (VHF CVD) process or a microwave plasma enhancedchemical vapour deposition (MW PECVD) process, for example. Further, thedeposition thicknesses of the photoelectric conversion layer 230 can bedecided according to the users' requirements.

Thereafter, a plurality of second openings T2 are formed in thephotoelectric conversion layer 230 to expose a portion of the firstconductive layer 220, as shown in FIG. 4E. In this embodiment, themethod of forming the second openings T2 is by performing a laserprocess, an etching process or a removing process using mechanicalforce, for example.

Afterwards, a passivation layer 250 is formed on the sidewall SW of eachsecond opening T2, as shown in FIG. 4F. In this embodiment, the methodof fainting the passivation layer 250 is by oxidizing the photoelectricconversion layer 230 at the sidewall SW of each second opening T2 with aCO₂ plasma treatment P, so as to form the above-mentioned passivationlayer 250. In this embodiment, the thickness of the passivation layer250 can be adjusted by changing the process parameters of the CO₂ plasmatreatment P, such as time, gas pressure, output power, etc. In thisembodiment, the thickness of the passivation layer 250 is substantiallybetween 0.1 nm and 10 nm. In some embodiments, the thickness of thepassivation layer 250 is substantially between 1 nm and 5 nm. Further,in some embodiments, the passivation layer 250 can be a native oxidelayer of the photoelectric conversion layer 230.

In details, before the step of FIG. 4F is performed, a thinner oxidelayer is formed on the top of the photoelectric conversion layer 230;thus, during the step of forming the CO₂ plasma treatment P, excessoxide is not easily formed on the top of the photoelectric conversionlayer 230 to increase the series resistance between the photoelectricelements 202. In another embodiment, a polishing or like process can beformed, after the CO₂ plasma treatment P, to reduce the thickness of theoxide layer on the top of the photoelectric conversion layer 230. Theabove-mentioned methods of forming the passivation layer 250 areprovided only for illustration purposes, and are not construed aslimiting the present invention. In yet another embodiment, thepassivation layer 250 having the above-mentioned material can be formedon the sidewall SW through a suitable process.

Thereafter, the above-mentioned second conductive layer 240 is formed onthe photoelectric conversion layer 230, wherein the second conductivelayer 240 is electrically connected to the first conductive layer 220through the second openings T2, as shown in FIG. 4G. The secondconductive layer 240 usually serves as top electrodes of the pluralityof photoelectric elements 202. In this embodiment, the method of formingthe second conductive layer 240 is by performing the above-mentionedsputtering process, MOCVD process, or evaporation process, for example.The material of the second conductive layer 240 is the material of theabove-mentioned transparent conductive layer, and the details are notiterated herein.

Afterwards, the step of FIG. 4H can be optionally performed. Referringto FIG. 4H, a laser process, an etching process or a removing processusing mechanical force is used to simultaneously form a plurality ofthird openings T3 to expose a portion of the first conductive layer 220.The manufacturing process of the thin film solar cell 200 as shown inFIG. 2 is thus completed.

It is noted that in one case, the second conductive layer 240 is astacked structure of a transparent conductive layer and a reflectivelayer, and the first conductive layer 220 is a transparent conductivelayer. Herein, a transparent conductive layer is formed on thephotoelectric conversion layer 230, and a reflective layer is thenformed on the transparent conductive layer. Thereafter, the process stepin FIG. 4H is performed so as to form a thin film solar cell withone-sided illumination.

In another case, the first conductive layer 220 can be a stackedstructure of a transparent conductive layer and a reflective layer, soas to form another thin film solar cell with one-sided illumination. Themanufacturing method has been described above, and the details are notiterated herein. Herein, it is noted that the second conductive layer240 can only be a transparent conductive layer.

Second Embodiment

FIG. 5 schematically illustrates a local cross-sectional view of a thinfilm solar cell according to another embodiment of the presentinvention. Referring to FIG. 5, in this embodiment, a thin film solarcell 200′ includes a substrate 210′, a first conductive layer 220′, aphotoelectric conversion layer 230′, a second conductive layer 240′ anda blocking material 250′. In this embodiment, the substrate 210′ can bea transparent substrate, such as a glass substrate.

The first conductive layer 220′ is disposed on the substrate 210′, andhas a plurality of first openings 222′ to expose a portion of thesubstrate 210′. The first conductive layer 220′ usually serves as frontelectrodes of a plurality of sub cells connected in series. In thisembodiment, the first conductive layer 220′ can include the material ofthe above-mentioned first conductive layer 220, and the details are notiterated herein. Similarly, the first conductive layer 220′ can be astacked layer of a reflective layer (not shown) and the above-mentionedtransparent conductive layer, and the reflective layer is disposedbetween the transparent conductive layer and the substrate 210′. Thematerial of the reflective layer can be a metal with higherreflectivity, such as silver (Ag) or aluminium (Al).

The photoelectric conversion layer 230′ is disposed on the firstconductive layer 220′, and has a plurality of second openings 232′ toexpose a portion of the first conductive layer 220′. The photoelectricconversion layer 230′ is physically connected to the substrate 210′through the first openings 222′. In this embodiment, the photoelectricconversion layer 230′ can include the described structure or possibleimplantation of the above-mentioned photoelectric conversion layer 230,and the details are not iterated herein.

That is, the thin film solar cell 200′ can at least include the filmlayer structure of an amorphous silicon thin film solar cell, amicrocrystalline silicon thin film solar cell, a tandem thin film solarcell, a triple thin film solar cell, a CIS thin film solar cell, a CIGSthin film solar cell, a GdTe thin film solar cell or an organic thinfilm solar cell. In other words, the photoelectric conversion layer 230′of this embodiment is provided only for illustration purposes, and canbe decided according to the users' requirements. The photoelectricconversion layer 230′ can also include the film layer structure ofanother suitable thin film solar cell.

Referring to FIG. 6, when a tandem thin film solar cell is taken as anexample, the photoelectric conversion layer 230′ can be a stacked layerof a first semiconductor stacked layer 234′ and a second semiconductorstacked layer 236′. The first semiconductor stacked layer 234′ has afirst-type semiconductor layer 234 a′, a first intrinsic layer 234 b′and a second-type semiconductor layer 234 c′, for example. The secondsemiconductor stacked layer 236′ has a third-type semiconductor layer236 a′, a second intrinsic layer 236 b′ and a fourth-type semiconductorlayer 236 c′, for example. The first-type semiconductor layer 234 a′ ofthe first semiconductor stacked layer 234′ and the third-typesemiconductor layer 236 a′ of the second semiconductor stacked layer236′ can be P-type semiconductor layers, while the second-typesemiconductor layer 234 c′ of the first semiconductor stacked layer 234′and the fourth-type semiconductor layer 236 c′ of the secondsemiconductor stacked layer 236′ can be N-type semiconductor layers. Inother words, in this embodiment, the first semiconductor stacked layer234′ and the second semiconductor stacked layer 236′ form a PINsemiconductor stacked structure. However, the present invention is notlimited thereto.

In another embodiment, the first-type semiconductor layer 234 a′ of thefirst semiconductor stacked layer 234′ and the third-type semiconductorlayer 236 a′ of the second semiconductor stacked layer 236′ can beN-type semiconductor layers, while the second-type semiconductor layer234 c′ of the first semiconductor stacked layer 234′ and the fourth-typesemiconductor layer 236 c′ of the second semiconductor stacked layer236′ can be P-type semiconductor layers. In addition, in anotherembodiment, the first semiconductor stacked layer 234′ and the secondsemiconductor stacked layer 236′ described above do not have the firstintrinsic layer 234 b′ and the second intrinsic layer 236 b′ and form aPN semiconductor stacked structure.

Referring to FIG. 5 again, the second conductive layer 240′ is disposedon the photoelectric conversion layer 230′, and has a plurality of thirdopenings 242′ to expose a portion of the first conductive layer 220′ anda portion of the side surface of the photoelectric conversion layer230′. The third openings 242′ and a portion of the second openings 232′are disposed at the same positions, and the second conductive layer 240′is physically connected to the first conductive layer 220′ through thesecond openings 232′. In this embodiment, the thin film solar cell 200′is divided into a photoelectric conversion region P1 and an isolationregion P2 by the third openings 242′, as shown in FIG. 5. Further, thesecond conductive layer 240′ can include the material of theabove-mentioned transparent conductive layer, and the details are notiterated herein. In this embodiment, the second conductive layer 240′can further include a reflective layer disposed on the transparentconductive layer.

It is noted that when the second conductive layer 240′ includes areflective layer, the first conductive layer 220′ can only be atransparent conductive layer. On the contrary, when the first conductivelayer 220′ includes a reflective layer, the second conductive layer 240′can only be a transparent conductive layer without a reflective layerthereon. In another embodiment, each of the first conductive layer 220′and the second conductive layer 240′ can be a single transparentconductive layer without a reflective layer thereon. In other words, thedesign of the first conductive layer 220′ and the second conductivelayer 240′ can be adjusted according to the users' requirements (e.g.for manufacturing a thin film solar cell with double-sided illuminationor a thin film solar cell with one-sided illumination). The design ofthe first conductive layer 220′ and the second conductive layer 240′described above is provided only for illustration purposes, and is notconstrued as limiting the present invention.

The blocking material 250′ fills in the third openings 242′ and at leastcovers the first conductive layer 220′ and the sidewall of thephotoelectric conversion layer 230′ which are exposed by the thirdopenings 242′, as shown in FIG. 5. In this embodiment, the blockingmaterial 250′ is mainly for protecting the first conductive layer 220′,the sidewall of the photoelectric conversion layer 230′, and thesidewall of a portion of the second conductive layer 240′ which areexposed by the third openings 242′, so that degradation of film layerscaused by moisture penetration is avoided and the leakage currentpossibly generated at the first conductive layer 220′ and at the sidesurface of the photoelectric conversion layer 230′ is reduced.Accordingly, the electrical performance of the thin film solar cell 200′is further improved.

In details, when the first conductive layer 220′, the photoelectricconversion layer 230′ and the second conductive layer 240′ in theisolation region P2 are not completely removed or not electricallyisolated from the photoelectric conversion region P1, a photo current isgenerated as the photoelectric conversion layer 230′ in the isolationregion P2 is illuminated. Similarly, a leakage current may be generatedon the first conductive layer 220′, on the side surface of thephotoelectric conversion layer 230′ and on the side surface of thesecond conductive layer 240′ in the isolation region P2. Thus, fillingthe blocking material in the third openings 242′ is beneficial toincrease the short circuit current (Isc) and shunt resistance of thethin film solar cell 200′. When the shunt resistance is increased, theleakage current is usually decreased accordingly. Therefore, thephotoelectric conversion efficiency of the thin film solar cell 200′ isimproved, so that the thin film solar cell 200′ has a better electricalperformance. In this embodiment, the blocking material 250′ includes aninsulating material, wherein the insulating material includes aninorganic material or an organic material. The inorganic material can besilicon oxide, silicon nitride, silicon oxynitirde, silicon carbide,hafnium oxide, aluminum oxide or a combination thereof, for example. Theorganic material can be photoresist, benzocyclobutane (BCB),cycloolefin, polyimide, polyamide, polyester, polyalcohols,polyethylene, polyphenylene, resin, polyether, polyketone or acombination thereof, for example.

In brief, the thin film solar cell 200′ of this embodiment has theabove-mentioned blocking material 250′ to cover the first conductivelayer 220′ and the side surface of the photoelectric conversion layer230′ which are exposed by the third openings 242′, so that degradationof film layers caused by moisture penetration is avoided, and the shortcircuit current (Isc) and shunt resistance are increased to reduce theleakage current possibly generated at the first conductive layer 220′and at the side surface of the photoelectric conversion layer 230′.Accordingly, the electrical performance and photoelectric conversionefficiency of the thin film solar cell 200′ are further improved.

In addition, the present invention also provides a manufacturing methodof the above-mentioned thin film solar cell 200′, which is described inthe following.

FIGS. 7A to 7H schematically illustrate a process flow of manufacturinga thin film solar cell according to an embodiment of the presentinvention. Referring to FIG. 7A, the above-mentioned substrate 210′ isprovided. The substrate 210′ can be a transparent substrate, such as aglass substrate.

Referring to FIG. 7B, the above-mentioned first conductive layer 220′ isformed on the substrate 210′. The first conductive layer 220′ includesthe material of the above-mentioned transparent conductive layer, andthe forming method thereof is by performing a sputtering process, ametal organic chemical vapour deposition (MOCVD) process or anevaporation process, for example.

Referring to FIG. 7C, the above-mentioned first openings 222′ are formedin the first conductive layer 220′ to expose a portion of the substrate210′. Accordingly, front electrodes of a plurality of sub cellsconnected in series are formed. In this embodiment, the method offorming the first openings 222′ is by patterning the first conductivelayer 220′ with a laser process, for example.

Referring to FIG. 7D, the above-mentioned photoelectric conversion layer230′ is formed on the first conductive layer 220′. In this embodiment,the method of forming the photoelectric conversion layer 230′ includesforming the above-mentioned first semiconductor stacked layer 234′ onthe first conductive layer 220′ and then forming the above-mentionedsecond semiconductor stacked layer 236′ on the first semiconductorstacked layer 234′. In details, the method of forming the photoelectricconversion layer 230′ is by performing a radio frequency plasma enhancedchemical vapour deposition (RF PECVD) process, a vary high frequencyplasma enhanced chemical vapour deposition (VHF CVD) process or amicrowave plasma enhanced chemical vapour deposition (MW PECVD) process,for example. The above-mentioned forming method of the photoelectricconversion layer 230′ is provided only for illustration purposes, and isnot construed as limiting the present invention. The forming method ofthe photoelectric conversion layer 230′ can be adjusted depending on thefilm layer design (e.g. the structure of the above-mentioned Group IVthin film or II-VI compound semiconductor thin film) of thephotoelectric conversion layer 230′. Further, the deposition thicknessesof the first semiconductor stacked layer 234′ and the secondsemiconductor stacked layer 236′ can be decided according to the users'requirements.

Referring to FIG. 7E, the above-mentioned second openings 232′ areformed in the photoelectric conversion layer 230′ to expose a portion ofthe first conductive layer 220′. The first semiconductor stacked layer232′ of the photoelectric conversion layer 230′ is physically connectedto the substrate 210′ through the first openings 222′. In thisembodiment, the method of forming the second openings 232′ is bypatterning the photoelectric conversion layer 230′ with a laser process,for example.

Referring to FIG. 7F, the above-mentioned second conductive layer 240′is formed on the photoelectric conversion layer 230′. In thisembodiment, the second conductive layer 240′ and the first conductivelayer 220′ have the same forming method. That is, the method of formingthe second conductive layer 240′ is by performing the above-mentionedsputtering process, MOCVD process, or evaporation process, for example.The material of the second conductive layer 240′ is the material of theabove-mentioned transparent conductive layer, and the details are notiterated herein.

Referring to FIG. 7G, the above-mentioned third openings 242′ are formedin the second conductive layer 240′ to expose a portion of the firstconductive layer 220′ and a portion of the side surface of thephotoelectric conversion layer 230′. The second conductive layer 240′ isphysically connected to the first conductive layer 220′ through thesecond openings 232′. In this embodiment, the method of forming thethird openings 242′ is by patterning the second conductive layer 240′with a laser process, for example. Accordingly, back electrodes of theplurality of sub cells connected in series are formed. In thisembodiment, after the step of forming the third openings 242′, the thinfilm solar cell 200′ is divided to a photoelectric conversion region P1and an isolation region P2, as shown in FIG. 7G.

Referring to FIG. 7H, the above-mentioned blocking material 250′ isfilled in the third openings 242′. The blocking material 250′ covers thefirst conductive layer 220′, the side surface of the photoelectricconversion layer 230′, and the top and side surface of a portion of thesecond conductive layer 240′ which are exposed by the third openings242′. In this embodiment, during the step of forming the third openings242′, the blocking material 250′ can be simultaneously filled in thethird openings 242′. That is, when a laser is performed to form thethird openings 242′, the blocking material 250′ accompanying the lasercan be simultaneously filled in the third openings 242′. Accordingly,degradation of film layers caused by moisture penetration is avoided,and the short circuit current (Isc) and shunt resistance of the thinfilm solar cell 200 are increased to reduce the leakage current possiblygenerated at the first conductive layer 220′ and at the side surface ofthe photoelectric conversion layer 230′. In addition, the method offilling the blocking material 250′ is by performing a dispensingprocess, an ink-jet printing process, a print screening process, a dryfilm lamination process or a coating process, for example.

In another embodiment, the step of filling the blocking material 250′can be performed after the step of forming the third openings 242′. Thesequence of forming the blocking material 250′ and the third openings242′ is decided according to the users' requirements and designs. Themanufacturing method of the thin film solar cell 200′ is thus completed.

It is noted that when the second conductive layer 240′ is a stackedstructure of a transparent conductive layer and a reflective layer, thefirst conductive layer 220′ is a transparent conductive layer. Herein, atransparent conductive layer is formed on the photoelectric conversionlayer 230′, and a reflective layer is then formed on the transparentconductive layer. Thereafter, the process step in FIG. 7H is performedso as to form a thin film solar cell with one-sided illumination. Inanother case, the first conductive layer 220′ can be a stacked structureof a transparent conductive layer and a reflective layer, so as to formanother thin film solar cell with one-sided illumination. Themanufacturing method has been described above, and the details are notiterated herein. Herein, it is noted that the second conductive layer240′ can only be a transparent conductive layer.

Third Embodiment

FIG. 8 schematically illustrates a local cross-sectional view of a thinfilm solar cell according to another embodiment of the presentinvention. Referring to FIG. 8, in this embodiment, a thin film solarcell 300 includes a substrate 310, a first conductive layer 320, aphotovoltaic layer 330, a second conductive layer 340 and a passivationlayer 350. In this embodiment, the substrate 310 can be a transparentsubstrate, such as a glass substrate.

The first conductive layer 320 is disposed on the substrate 310, and hasa plurality of first openings 322 to expose the substrate 310, as shownin FIG. 8. In this embodiment, the first conductive layer 320 can be atransparent conductive layer, and the material thereof can be at leastone of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zincoxide (ITZO), zinc oxide, aluminium tin oxide (ATO), aluminium zincoxide (AZO), cadmium indium oxide (CIO), cadmium zinc oxide (CZO),gallium zinc oxide (GZO) and fluorine tin oxide (FTO).

In another embodiment (not shown), the first conductive layer 320 can bea stacked layer of a reflective layer (not shown) and theabove-mentioned transparent conductive layer, and the reflective layeris disposed between the transparent conductive layer and the substrate310. The material of the reflective layer can be a metal with higherreflectivity, such as silver (Ag) or aluminium (Al).

Referring to FIG. 8, the photovoltaic layer 330 is disposed on the firstconductive layer 320, and has a plurality of second openings 332 toexpose the first conductive layer 320. In this embodiment, thephotovoltaic layer 330 can be a Group IV thin film, a III-V compoundsemiconductor thin film, a II-VI compound semiconductor thin film or anorganic compound semiconductor thin film. In details, the Group IV thinfilm includes at least one of an amorphous silicon (a-Si) thin film, amicrocrystalline silicon (μc-Si) thin film, an amorphous silicongermanium (a-SiGe) thin film, a microcrystalline silicon germanium(μc-SiGe) thin film, an amorphous silicon carbide (a-SiC) thin film, amicrocrystalline silicon carbide (μc-SiC) thin film, a tandem siliconthin film and a triple silicon thin film, for example. The III-Vcompound semiconductor thin film includes a gallium arsenide (GaAs) thinfilm, an indium gallium phosphide (InGaP) thin film or a combinationthereof, for example. The II-VI compound semiconductor thin film can bea copper indium diselenide (CIS) thin film, a copper indium galliumdiselenide (CIGS) thin film, a cadmium telluride (CdTe) thin film or acombination thereof, for example. The organic compound semiconductorthin film includes a mixture of poly(3-hexylthiophene) (P3HT) and PCBM,for example.

That is, the thin film solar cell 300 can at least include the filmlayer structure of an amorphous silicon thin film solar cell, amicrocrystalline silicon thin film solar cell, a tandem thin film solarcell, a triple thin film solar cell, a CIS thin film solar cell, a CIGSthin film solar cell, a GdTe thin film solar cell or an organic thinfilm solar cell.

Therefore, the photovoltaic layer 330 of this embodiment is providedonly for illustration purposes, and is not construed as limiting thepresent invention. The photovoltaic layer 330 can be decided accordingto the users' requirements. In other words, the thin film solar cell 300can also include the film layer structure of another suitable thin filmsolar cell.

Further, the second conductive layer 340 is disposed on the photovoltaiclayer 330 and electrically connected to the first conductive layer 320through the second openings 332. The second conductive layer 340 has aplurality of third openings 342 to expose the first conductive layer 320and the sidewall of the photovoltaic layer 330, as shown in FIG. 8. Inthis embodiment, the second conductive layer 340 can be a transparentconductive layer and includes the material of the first conductive layer320, and the details are not iterated herein. In this embodiment, thesecond conductive layer 340 can further include a reflective layerdisposed on the transparent conductive layer. It is noted that when thesecond conductive layer 340 includes a reflective layer, the firstconductive layer 320 can only be a transparent conductive layer. On thecontrary, when the first conductive layer 320 includes a reflectivelayer, the second conductive layer 340 can only be a transparentconductive layer without a reflective layer thereon. In an embodiment,each of the first conductive layer 320 and the second conductive layer340 can be a single transparent conductive layer without a reflectivelayer thereon. In other words, the design of the first conductive layer320 and the second conductive layer 340 can be adjusted according to theusers' requirements (e.g. for manufacturing a thin film solar cell withdouble-sided illumination or a thin film solar cell with one-sidedillumination). The design of the first conductive layer 320 and thesecond conductive layer 340 described above is provided only forillustration purposes, and is not construed as limiting the presentinvention.

Referring to FIG. 8, the passivation layer 350 covers the secondconductive layer 340 and the sidewall 330 a of the photovoltaic layer330 in the third openings 342. In this embodiment, the material of thepassivation layer 350 can be a reflective material, such as a lead paintor a metal. In details, the passivation layer 350 covers the secondconductive layer 340 and the sidewall 330 a of the photovoltaic layer330 in the third openings 342, so as to protect the film layers 320, 330and 340 from being affected by the external environment such asmoisture. Further, the passivation layer 350 of this embodiment coversthe sidewall 330 a of the photovoltaic layer 330 in the third openings342, so as to prevent surface recombination of the electron-hole pairsfrom occurring at the sidewall 330 a of the photovoltaic layer 330 inthe third openings 342; thus, a leakage current is not generated. Inother words, in the thin film solar cell 300 of this embodiment, thepassivation layer 350 substantially covers the second conductive layer340 and the sidewall 330 a of the photovoltaic layer 330 in the thirdopenings 342, so that the possibility of generating leakage current isreduced, and the photoelectric conversion efficiency of the thin filmsolar cell 300 is further improved.

In addition, when the material of the passivation layer 350 is areflective material, the light re-utilization rate inside thephotovoltaic layer 320 is enhanced, and the photoelectric conversionefficiency of the thin film solar cell 300 is further improved. It isnoted that when the passivation layer 350 includes a reflectivematerial, the first conductive layer 320 do not need the above-mentionedreflective layer. In an embodiment, the passivation layer 350 caninclude a solid solute and a liquid solvent, and the solids content ofthe passivation layer 350 is no less than 30%.

In another embodiment, the passivation layer 350 can be an organicpassivation layer. Accordingly, the method of covering the organicpassivation layer 350 on the second conductive layer 320 and on thesidewall 330 a of the photovoltaic layer 330 includes providing anorganic solution (not shown), and then coating the organic solution onthe second conductive layer 320 through a coating process. Since theviscosity coefficient of the organic solution is lower, the organicsolution can flow into the third openings 342 easily to cover thesidewall 330 a of the photovoltaic layer 330. At this time, if a shortertime is desired to cure the organic solution to the organic passivationlayer 350, a heat curing treatment can be performed to the organicsolution on the second conductive layer 320 and on the sidewall 330 a ofthe photovoltaic layer 330 in the third openings 342, and thus, theorganic solution can be cured to the organic passivation layer 350 morequickly.

In another embodiment, the passivation layer 350 can be an insulatingpassivation layer. The method of covering the insulating passivationlayer 350 on the second conductive layer 320 and on the sidewall 330 aof the photovoltaic layer 330 includes performing a deposition process,a print screening process, a dry film lamination process, a coatingprocess, a ink-jet printing process or a energy source treatment. Inanother embodiment, the insulating passivation layer 350 can be formedon the second conductive layer 320 and on the sidewall 330 a of thephotovoltaic layer 330 through a plasma oxidation process. The plasmaoxidation process can be a CO₂ plasma oxidation process, for example. Inyet another embodiment, the second conductive layer 340 and the sidewall330 a of the photovoltaic layer 330 in the third openings 342 can beexposed to air to form a native oxide layer, wherein the native oxidelayer is the insulating passivation layer 350 of this embodiment. Inother words, the method of forming the insulating passivation layer 350depends on the users' requirements. The above-mentioned forming methodsare provided only for illustration purposes, and are not construed aslimiting the present invention.

In summary, the thin film solar cell of the present invention has thepassivation layer disposed between the photovoltaic conversion layer andthe second conductive layer. Therefore, when the thin film solar cell isilluminated to process a photoelectric conversion, the generatedelectron-hole pairs are not easy to recombine near the interface betweenthe photoelectric conversion layer and the second conductive layer. Inother words, the thin film solar cell of the present invention canexhibit a higher photoelectric conversion efficiency. Further, theabove-mentioned passivation layer can be easily formed through simplesteps described in the manufacturing method of the present invention, sothat the characteristics of the thin film solar cell are accordinglyenhanced.

In addition, the thin film solar cell of the present invention has theblocking material to cover the first conductive layer and the sidesurface of the photoelectric conversion layer which are exposed by thethird openings. Therefore, degradation of film layers caused by moisturepenetration is avoided, and the short circuit current (Isc) and shuntresistance are increased to reduce the leakage current possiblygenerated at the first conductive layer and at the side surface of thephotoelectric conversion layer. Accordingly, the electrical performanceand photoelectric conversion efficiency of the thin film solar cell arefurther improved.

Besides, in the thin film solar cell of the present invention, thepassivation layer having an insulating property covers the sidewall ofthe photovoltaic layer in the third openings, so as to prevent surfacerecombination of electron-hole pairs from occurring at the sidewall ofthe photovoltaic layer in the openings. Accordingly, the photoelectricconversion efficiency of the thin film solar cell is enhanced. Further,in the manufacturing method, at least one coating process is performed,so that the passivation layer substantially covers the sidewall of thephotovoltaic layer in the openings to achieve the above-mentionedadvantages.

The present invention has been disclosed above in the preferredembodiments, but is not limited to those. It is known to persons skilledin the art that some modifications and innovations may be made withoutdeparting from the spirit and scope of the present invention. Therefore,the scope of the present invention should be defined by the followingclaims.

1. A thin film solar cell, comprising: a substrate; a first conductivelayer, disposed on the substrate, and having a plurality of firstopenings so that the first conductive layer is divided into bottomelectrodes of a plurality photovoltaic elements; a photoelectricconversion layer, disposed on the first conductive layer and having aplurality of second openings to expose a portion of the first conductivelayer; a second conductive layer, disposed on the photoelectricconversion layer and connected to the first conductive layer through thesecond openings, wherein the second conductive layer has a plurality ofthird openings to exposed a portion of the first conductive layer; and apassivation layer, disposed on a sidewall of each second opening andbetween the photoelectric conversion layer and the second conductivelayer, so that the second conductive layer in the second openings iselectrically isolated from the photoelectric conversion layer.
 2. Thethin film solar cell of claim 1, wherein a thickness of the passivationlayer is substantially between 0.1 nm and 10 nm.
 3. The thin film solarcell of claim 2, wherein the thickness of the passivation layer issubstantially between 1 nm and 5 nm.
 4. The thin film solar cell ofclaim 1, wherein a material of the passivation layer comprises adielectric material, an insulating material or a compound materialcontaining oxygen or nitrogen.
 5. The thin film solar cell of claim 4,wherein the material of the passivation layer comprises silicon oxide,silicon nitride or silicon oxynitride.
 6. The thin film solar cell ofclaim 1, wherein the photoelectric conversion layer comprises afirst-type semiconductor layer and a second-type semiconductor layer. 7.The thin film solar cell of claim 1, wherein the photoelectricconversion layer comprises a double-layer photoelectric conversionlayer, a triple-layer photoelectric conversion layer or a stackedstructure of more than three photoelectric conversion layers.
 8. Thethin film solar cell of claim 1, wherein the first conductive layer is atransparent conductive layer, and the second conductive layer comprisesat least one of a reflective layer and a transparent conductive layer.9. The thin film solar cell of claim 1, wherein the second conductivelayer is a transparent conductive layer, and the first conductive layercomprises at least one of a reflective layer and a transparentconductive layer.
 10. A manufacturing method of a thin film solar cell,comprising: providing a substrate; forming a first conductive layer onthe substrate; forming a plurality of first openings in the firstconductive layer, so that the first conductive layer is divided tobottom electrodes of a plurality of photovoltaic elements; forming aphotoelectric conversion layer on the first conductive layer; forming aplurality of second openings in the photoelectric conversion layer toexpose a portion of the first conductive layer; forming a passivationlayer on sidewalls of the second openings; and forming a secondconductive layer on the photoelectric conversion layer, wherein thesecond conductive layer is connected to the first conductive layerthrough the second openings, and the second conductive layer has aplurality of third openings to expose a portion of the first conductivelayer, wherein the passivation layer is disposed between thephotoelectric conversion layer and the second conductive layer, so thatthe second conductive layer in the second openings is electricallyisolated from the photoelectric conversion layer.
 11. The manufacturingmethod of claim 10, wherein a method of forming the passivation layercomprises forming a native oxide layer of the photoelectric conversionlayer or performing a plasma treatment to the photoelectric conversionlayer.
 12. The manufacturing method of claim 10, wherein a method offorming the first openings, the second openings or the third openingscomprises performing a laser process, an etching process or a removingprocess using mechanical force. 13-27. (canceled)